1. Field of the Invention
The present invention relates to a thermal transfer recording apparatus, which records an image on a recording medium by transferring ink of an ink sheet on the recording medium, and a facsimile apparatus using this apparatus.
2. Related Background Art
A thermal transfer printer generally uses an ink sheet obtained by applying heat fusible (or heat sublimable) ink on a base film, and selectively heating the ink sheet in accordance with the image signal by a thermal head to transfer the fused (or sublimated) ink on the recording sheet for image recording. Since the ink is generally transferred completely to the recording sheet (so-called one-time sheet) by recording the image at a time on this ink sheet, after recording the image of one character or one line, it was necessary to convey the ink sheet by a length corresponding to the length of the recording, and next to securely bring a portion, on which the ink sheet has not yet been used, to the next position to be recorded.
Since this increases the usage of the ink sheets, the running cost for the thermal transfer printer has had a tendency to be higher than that for an ordinary thermal printer which records on thermal paper.
To solve this problem at issue, a thermal transfer printer has been proposed which the recording sheet and ink sheet are conveyed to provide a difference in speed as shown in the Publication of U.S. Pat. No. 4,456,392, Japanese Laid-Open Patent Application No. 58-201686 and Japanese Patent Publication No. 62-58917. As specified in the above publications, an ink sheet (multi-print sheet) capable of recording the image plural (n) times is known.
When the length of recording is L and is continuously recorded, a length of conveyance of the ink sheet, which is conveyed after recording each image or while the image is being recorded, can be made smaller than its length L (L/n:n&gt;1) for recording by using this ink sheet. This increases the usage efficiency of ink sheet n times conventional one, and the reduction in the running cost of the thermal transfer printer can be expected. Hereinafter this recording system is called "Multi-print".
When generally recording in a facsimile apparatus, etc., while receiving image signals, the recording time interval for one line does not remain constant, causing so-called intermittent recording because the time needed to decode image signals after receiving differs with image signals for each line. However, in a facsimile apparatus equipped with a large capacity image memory, which records images after storing the received image signal in its memory once, it is possible to record at uniform speed by making the recording time interval for one line constant.
In an ordinary thermal transfer printer, the uniform speed recording (such as continuous recording), in which the recording time interval for each line is constant facilitates recording because of predictable heat dissipation, etc. of the thermal head, and so is superior in the quality of recording because recording density variation decreases. If, therefore, the above n value is fixed to meet such an uniform speed recording, the difference in quality of recording between uniform speed recording and intermittent recording is likely to conspicuously appear when both recordings are performed.